Sliding buckle for a rescue sling

ABSTRACT

A sliding buckle for straps with a largely U-shaped base part in which a wing is mounted for, together with the U-shaped base part, encircling an aperture intended for a strap extending through the aperture, where the wing is mounted pivotably about an axis so that pivoting of the wing about the axis reduces or enlarges the aperture, where pull from a strap bearing against the rear wing section of the wing and having a direction with a component perpendicularly to the base part forces the wing to pivot about the axis in order thereby to reduce the aperture for securely locking the strap in the aperture.

[0001] By rescue actions in mountain areas or at sea, where people in distress are to be hoisted up by ropes, it is common to use rescue slings that are laid around the waist of the person to be rescued. Typically, a rescuer will be hoisted down to the person, e.g. in a rock crevice or on a life raft at sea, after which the rescuer aids by laying the rescue sling around the waist of the distressed person, which is then hoisted, e.g. in a rescue helicopter. In the simplest version, such a rescue sling is constituted by a sling surrounding the distressed person. The sling is prevented from sliding off the person by it being placed under the armpits. In some rescue situations it has occurred, however, that the distressed person to be hoisted has slid out of the sling, a fact which has led to development of a number of safety mechanisms for preventing such accidents.

[0002] In the U.S. Pat. No. 4,396,091 there is thus mentioned a buckle for a belt which is largely formed as a sling. In one the embodiments described, this safety mechanism is formed as a ring with a centre bar, so that the ring has two apertures in which the rope, which is fastened to both ends of the sling, is extending. After placing a person in the sling, this ring can be displaced along the rope towards the distressed person, thereby reducing the circumference of the sling around the distressed person. In another embodiment described in this patent, the safety mechanism is a buckle fastened at one end of the sling, and where the other end of the sling extends through a second aperture of this buckle. After placing a person in this sling, the length of the sling may also be decreased and ensure that the sling is not so large that the distressed person slides out of the sling.

[0003] For both of these safety mechanisms it is true that they after tightening are difficult to loosen again so that the circumference of the sling becomes larger. This is particularly true if the sling and the ropes connected with the sling become wet and possibly freeze at low temperatures. In case the sling is to be made greater so that it can be fitted one in distress, it is a great disadvantage that the safety mechanism cannot be loosened in a simple way. This is particularly a problem when several people are to be rescued one by one, e.g. from a ship in distress, where it is necessary to adapt the sling the size of the person, and where it is also important that the sling can be removed very quickly from the person when he has been hoisted up into the rescue helicopter.

[0004] Another safety mechanism is known from U.S. Pat. No. 5,740,591. This safety mechanism consists of a buckle with a lever arm which by actuation presses part of the belt against a base to which the belt is fastened. By regulating the length of the belt, which extends through the buckle, the sling, which e.g. is used for rescuing people in distress, be adjusted in length. This buckle requires some force in order to be activated and thus also requires relatively great force releasing the belt again. In a cold, wet and turbulent environment, as is the case under rescue operations at sea, it may be very difficult for a rescuer to loosen such a buckle. Particularly if the fingers of the rescuer are cold and wet, it will be very difficult to loosen the buckle by pulling the lever arm.

[0005] Therefore, it is the purpose of the invention to provide an improved safety mechanism for lifting straps.

[0006] This purpose is achieved by a sliding buckle for straps as described in claim 1.

[0007] The sliding buckle according to the invention has a substantially U-shaped base part in which a wing is mounted so that between the U-shaped base part and the wing an aperture intended for a strap appears. Preferably, the U-shaped base part is disposed between two side elements between which the wing is also fitted. The term “U-shaped” for the base part is to be viewed as a simplified structural term and is not to be regarded as limiting for the design of the base part itself, which also can be made as e.g. a V. This depends on the preferred construction which the skilled in the art will choose in the actual case, which is not, however, restricting the inventive principle. The wing in the sliding buckle is mounted pivotably about an axis so that pivoting the wing about this axis decreases and increases, respectively, the aperture. If the aperture is sufficiently decreased, the strap will be secured in the aperture by squeezing, as it is decisive for the function of the sliding buckle that the aperture can be reduced sufficiently for the strap to be secured therein. If the wing is pivoted oppositely, the strap will be released and may slide in the aperture of the sliding buckle.

[0008] It is thus the intention with the sliding buckle that it acts self-locking. Such a function can be attained in the following way. If pull arises in the strap when this abuts on the rear wing section of the wing in direction with a component perpendicularly to the base part, the rearmost part of the wing is forced in direction away from the base part, whereby the wing pivots about the axis, whereby the foremost part of the wing is pressed in direction against the base part, whereby the aperture is reduced, and the strap is clamped in the aperture.

[0009] The typical field of application for such a slide buckle is for rescue straps for rescuing humans or animals. A simple form of such a rescue strap consists of a sling with two ends which can be provided with fastening means, e.g. rings for fastening a rescue rope. Both ends of the sling extends through a sliding buckle according to the invention. The sliding buckle may thus slide along the strap and thereby increase or decrease the aperture of the strap. If a man is e.g. placed in the strap, by a very simple and rapid movement of the rescuer the sliding buckle will be pushed close to the distressed person, whereby the strap from the rescue strap is adjusted to the circumference of the body of the distressed person. Since the strap is joined in the aperture of the sliding buckle, the base part and the wing of the sliding buckle will be pressed away from each other when the sliding buckle is relatively close the body of the distressed person, whereby the aperture is decreased and the sliding buckle is clamped around the strap from the sling. In this way it is prevented that the distressed person falls out of the strap during the rescue operation. After the rescuing, where the strap is relieved again, the force directed outward for the base part and the wing be reduced, whereby the aperture is increased again, and the belt is no longer secured. In case the sliding buckles have been positioned very close to the body so that the relief alone is not sufficient for loosening the sliding buckle, only a very slight pressure upon the wing in direction of the base part is required in order that the sliding buckle loosens its grip around the strap.

[0010] The principle of the sliding buckle is thereby very simple, reliable, and fast in operation.

[0011] In order to increase clamping of the strap in the aperture, the foremost wing section may be provided with teeth, which are intended for engaging the strap in the aperture when this is decrease for clamping.

[0012] Alternatively, it is possible that the base part is also provided with such teeth or points for engaging the strap.

[0013] The term strap in connection with the invention covers belts as well as ropes, seizings, or other analogous flexible fastening means. Such a strap may have different profiles, thus a belt is most often flat, whereas a robe usually has an approximately circular cross-section. In a further embodiment of the invention, the wing and/or the base part are provided with a profile in the aperture corresponding to the profile of the strap. Thus the wing and the base part may have parallel jaws for clamping flat belts. However, it would be advantageous that the jaws have a profile corresponding to one or more ropes if these extend through the aperture.

[0014] In order to use a sliding buckle according to the invention in an optimal way in connection with rope, it is suitable that the profile at the jaws in the aperture corresponds to the thickness of the rope. However, it may be an advantage if a sliding buckle according to the invention can be used for several rope dimensions. Such may be achieved with a sliding buckle according to the invention if this is provided with a convex notch in direction perpendicular to the axis, so that a change of the angle between wing and base part changes the profile corresponding to the rope in the area where the rope is secured in the aperture. A thin rope extending through the aperture will be clamped between the jaws in the aperture when the jaws are relatively close to each other. By designing the jaws, i.e. the wings, with such a convex notch, the jaw profile will depend on how much the wing is turned relative to the axis of pivot, which just implies that the same sliding buckle can be used with thin ropes as well as with thicker ropes.

[0015] As explained above, the sliding buckle in the above embodiment will only squeeze around the strap if an outwards directed force is applied to the wing relative to the base part. It is also possible to provide the sliding buckle according to the invention with a geometrically self-locking mechanism. In that case, the wing profile is designed so that the wing, by clamping, overcomes a geometrical dead point which is again to be overcome in the opposite direction of rotation of the wing for loosening the strap in the aperture.

[0016] It is also possible to provide the sliding buckle according to the invention with a further locking device, so that clamping of the strap can be made permanent. Such a locking device may e.g. be achieved with a pawl or snap lock blocking the wing relative to the base part.

[0017] It is preferred that the breech is secured to the side elements, thereby substantially making up the base part. However, it is within the scope of the invention that the breech in the base part is constituted by a further wing mounted pivotably between the side elements whereby the sliding buckle is substantially constituted by two pivotable wings, which are held together by two side elements.

[0018] A sliding buckle according to the invention will preferably find application as rescue strap. The use of a sliding buckle according to the invention, however, has far wider application and may also find application for lifting straps in forestry, e.g. for lifting tree trunks, for preventing the trunks from sliding out of the lift strap. In agriculture, such a sliding buckle may e.g. find application by lifting animals, machines or straw bales. Use of the sliding buckle may also be found within all kinds of transport of goods, particularly loading and unloading ship freight. A further application of such a sliding buckle is for safety belts in vehicle, preferably cars. In this case, the wing in the sliding buckle may advantageously be provided with a spring device, which pulls the rearmost part of the wing towards the base part in order thereby to loosen the clamping of the belt. Under load, e.g. by braking or collision, the belt will counteract the spring force due to the jerk from the passenger and reduce the aperture, whereby the jaws will retain the belt against sliding further through the aperture.

[0019] In order to increase the friction between the strap and the sliding buckle, particularly under wet conditions, it may be suitable to provide the strap with a coating having increased friction against the inner sides of the jaws of the sliding buckle. An increased friction of the strap in the sliding buckle is also achieved if threads are sewn or woven into the strap where the threads imply high friction against the sliding buckle. Such threads may e.g. consist of rubber. Decisive in this connection is that the frictional material is at least provided at the surface of the strap for enhancing friction with the jaws.

[0020] The invention with be explained further in the following with reference to the drawing, where:

[0021]FIG. 1 shows a sliding buckle according to the invention as seen towards the jaws of the aperture,

[0022]FIG. 2 shows a sliding buckle according to the invention as seen from the back side,

[0023]FIG. 3 shows a sliding buckle with straps through the aperture,

[0024]FIG. 4 shows a carrying strap with a sliding buckle according to the invention,

[0025]FIG. 5 shows the jaws of the sliding buckle with teeth,

[0026]FIG. 6 shows the jaws with a profile adapted for rope,

[0027]FIG. 7 shows the wing jaw provided with a convex notch,

[0028]FIG. 8 shows a cross-section of a geometrically self-locking wing,

[0029]FIG. 9 shows a strap with friction enhancing threads.

[0030]FIG. 1 shows a sliding buckle according to the invention having a substantially U-shaped base part 2 comprising a breech 3 and two side elements 4 and 4′. An axle 5 is fastened on the side elements 4 and 4′ and extend through the wing 6, which can rotate about the axis of rotation 5′ of this axle 5, illustrated with arrows 7, 8 and 8′. An aperture 9 is surrounded by the base part 4 and the wing 6. The aperture 9 is intended for a strap extending through the aperture 9. The size of the aperture 9 may be varied by rotation of the wing 6 so that the aperture 9 becomes lesser if the wing 6 is rotated in direction indicated with arrow 8, and the aperture 9 is enlarged if the wing 6 is rotated in direction indicated with arrow 8′. In case a strap extends through the aperture 9, this strap will be clamped between the jaws 10 and 11 on the breech 3 and the wing 6, respectively, if the wing 6 is rotated sufficiently in direction as indicated with arrow 8.

[0031] On FIG. 2, the sliding buckle 1 according to the invention is seen from behind towards the aperture 9. FIG. 3 shows the sliding buckle 1 where two straps 12, 12′ are running through the aperture 9 between the jaws 10,11 on the breech 3 and the wing 6, as one of the straps 12 are extended in direction to the left in the picture, i.e. in direction away from the base part. The wing 6 will thus be turned clockwise about the axis 5′, whereby the wing jaw 11 will press the straps 12,12′ against the breech 3, whereby the straps 12,12′ are clamped in the sliding buckle 1. The sliding buckle 1 will thereby no longer slide along the straps 12, 12′. If the pull in one strap 12 is slackened, there will not be exerted any force on the straps 12, 12′ between the jaws 11 and 10, and the sliding buckle 1 can slide along the straps 12,12′.

[0032] If the pull from one strap 12 cannot be sufficiently slacked of the sliding buckle 1 to be released from its engagement with the straps 12,12′, a relatively small pressure action will press the rearmost section 13 of the wing 6 in direction towards the base part 4, i.e. the wing 6 turns counter-clockwise, whereby the sliding lock 1 is released from its engagement.

[0033]FIG. 4 shows a rescue sling 14 comprising two strap ends 12 and 12′ running through the aperture in the sliding buckle 1 and ending in a pair of fastening devices 15, e.g. rings for fastening to a rescue rope. Such a simple sling may e.g. be used for rescuing people as described in the introduction. For such use, the rescue sling 14 is provided with a foam pad 16 extending along a part of the sling 14. Such a device may, however, also be used for hoisting other goods, e.g. tree trunks. If such goods are placed in the sling 14, the sliding buckle 1 in the start position will be placed close to the fastening devices 15 in order thereby to provide a large cross-sectional area of the sling 14 and thereby facilitate placing of the goods in the sling 14. Then the sliding buckle 1 will be pushed against the goods and by hoisting be secured in the locked position, so that the goods cannot slide out of the sling 14.

[0034] Besides, the rescue sling 14 comprises two further fastening means 25 which are intended for fastening other goods to be lifted with the sling. These other goods may e.g. another person to be hoisted together with this sling. The other person may a further person to be rescued, or the rescue assistant himself during a rescue operation. These two further fastening devices 25 may also be used for fastening goods of general character which are to be hoisted together with the sling 14.

[0035] The strap ends 12 and 12′ may advantageously be provided with reflecting material 26 at the surface of the strap. Such reflecting material may be advantageous when the rescue sling 14 is used in the dark, where searchlights are used as aid. If searchlights are not used, the reflecting material 26 may be substituted with fluorescent material, facilitating handling under a rescue operation.

[0036]FIG. 5 shows a sliding buckle according to the invention in a further development, where the wing 6 has a jaw 11, which is provided with teeth or points 18 for reinforcing securing of the strap through the sliding buckle 1. As alternative, the opposite jaw 10 only may also be provided with points or teeth, or both jaws 10 and 11 may be provided with corresponding teeth or analogous means.

[0037] On FIG. 6a is shown a sliding buckle 1 according to the invention, where the jaws 10 and 11 are provided with a profile 19,19′ corresponding to the profile of the strap, which in this case has a circular cross-section, which is typical for a rope.

[0038]FIG. 6b shows the wing 6 in perspective, where the jaw 11 is provided with the profile 19 shown in FIG. 6a. This profile 19 may also be provided with teeth for better securing the rope through the sliding buckle 1.

[0039] On FIG. 7 is shown the wing 6 when the jaw 11 is provided with a profile 19″, which is designed as a notch with convex notch wall 20, where the notch/profile 19″ extends perpendicularly to the axis of revolution 21 of the wing. If there is placed a thin rope through the aperture 9, for the securing of this rope it would be required that the wing 6 is turned relatively much by pressing the rearmost section 13 of the wing 6 outward in the sliding buckle 1. Thereby, primarily the foremost section of the jaw 11 will be used for securing this thin rope. In this position, the foremost part of the convex notch 19″ will just correspond to the profile of the thin rope. On the other hand, if a thick rope is placed in the aperture 9 of the sliding buckle 1 , less turning of the wing 6 about the axis of rotation 21 is needed, and the rope will be clamped between the jaws 10 and 11 in the part 22 of the notch 19″, which is located closer to the centre of the wing 6. As the notch 19″ is convex, the profile in this part of the wing 6 will just correspond to the profile of the thicker rope. Also the convex profile 19″ can be provided with teeth or points for better securing of the rope.

[0040] If suitable, it is possible to design the jaws with more than one profile, e.g. so that two or three ropes can be passed through the sliding buckle. The advantage of the above profiles 19, 19′ and 19″ is that ropes passing through the jaw will maintain their position in the aperture 9.

[0041]FIG. 8 shows a cross-sectional profile of a possible shape of a wing 6 for a sliding buckle 1 according to the invention. By turning the wing 6 about the axis of rotation 5′ clockwise, the strap 12, which is indicated with a stippled line, will be clamped between the wing jaw 11, cf. description above. If the wing 6 is turned so much that the foremost part of the jaw 11 squeezes the strap, the sliding buckle 1 with be geometrically self-locking, as the wing 6 in this case is turned out over the geometrical dead point 23. Also, a loosening of the sliding buckle 1 will require that the wing 6 is turned back counter-clockwise so the geometrical dead point 23 is overcome before the sliding buckle is loosened from the strap 12.

[0042] It is obvious for the skilled in the art to modify the sliding buckle 1 within the scope of the invention by including a pawl or snap lock for permanent locking of the sliding buckle. In this case, loosening of the sliding buckle from its position on the strap will require a deactivation of such a locking device.

[0043] It is within the scope of the invention to modify the sliding buckle according to the invention so that the base part is constituted substantially by a pair of side elements 4 and 4′ between which a breech 3 is fitted, where the breech constitutes a further wing mounted pivotably between the side elements 4 and 4′, quite analogous with the wing 6 mounted pivotably between the side elements 4 and 4′.

[0044] Furthermore, it will be possible to provide the side elements 4 and 4′ with stop elements, e.g. small integrated projections that limit the pivoting of the wing 6 and 3, respectively, in one or both directions, so that a minimum/maximum aperture 9 is defined.

[0045] A sliding buckle according to the invention may advantageously be made in plastic materials and in metal, preferably stainless steel. Polymer materials have the advantage that they are very resistant to chemical attack, are very stable and easy and cheap to make.

[0046] On FIG. 9 is shown a part of a strap 12 provided with friction inducing threads 24 which are sewn or woven into the strap 12. The upper part of FIG. 9 shows the strap in perspective whereas the lowermost part of FIG. 9 shows the strap 12 in cross-section. In the shown embodiment on FIG. 9, the friction inducing threads 24 extend to both sides of the strap 12. Strictly speaking, this is not necessary as it is sufficient that the strap has friction inducing threads on the side facing the jaws. However, it is preferred that the friction inducing threads on the surface of both sides of the belt. Friction inducing threads are, besides application in belts, also applicable to ropes with circular or other cross-section. 

1. A sliding buckle (1) for straps (12, 12′) with a largely U-shaped base part in which a wing (6) is mounted for, the wing having a front wing section and a rear wing section, the front wing section, together with the U-shaped base part (2), encircling an aperture intended for a strap (12, 12′) extending through the aperture (9), where the wing (6) is mounted pivotably about an axis (5′) so that pivoting of the rear wing (6) about the axis in a direction away from the base part forces the front wing section to pivot towards the base part to (5′) reduces or enlarges reduce the aperture (9), characterised in that the sliding buckle is configured such that pull from a strap (12, 12′) bearing against the rear wing section (13) of the wing (6) and having a direction with a component perpendicularly away from to the base part (2) forces the wing (6) to pivot about the axis (5′) in order thereby to reduce the aperture (9) for securely locking the strap (12, 12′) in the aperture (9).
 2. A sliding buckle (1) according to claim 1, wherein the front wing section (11) is provided with teeth (18) intended for engaging the strap (12, 12′) in the aperture (9).
 3. A sliding buckle (1) according to claim 1 or 2, wherein the wing (6) and/or the base part, or the wing and the base part (2) are/is are provided with a profile (19, 19′,19″) in the aperture corresponding to the profile of the strap (12, 12′).
 4. A sliding buckle (1) according to claim 1, 2 or 3, wherein the wing (6) and/or the base part, or the wing and the base part (2) are/is are provided with a convex notch (19″) in a direction perpendicular to the axis (5′), so that changing the angle between the wing and the base part (2) changes the profile (19″) corresponding to the strap (12, 12′) in the area where the strap is secured in the aperture. (9).
 5. A sliding buckle (1) according to any preceding claim claim 1, wherein the front part of the wing (6) at the side intended for bearing against the strap (12, 12′) in the aperture (9) is provided with a geometrically self-locking wing profile, where the wing (6) by clamping or loosening the strap (12, 12′) overcomes a geometrical dead point (23).
 6. A sliding buckle (1) according to any preceding claim claim 1, wherein the base part (2) is substantially constituted by a pair of side elements (4, 4′) between which a breech (3) is fitted, where the breech (3) is constituted by a further wing fitted pivotably between the side elements (4, 4′).
 7. A sliding buckle (1) according to any preceding claim claim 1, wherein the wing (6) and/or or the breech, or the wing and the breech (3) are/is are provided with a further locking device, preferably a pawl or snap lock, for permanent locking of the sliding buckle (1).
 8. A lifting Use of a sliding buckle (1) according to any preceding claim for at least one purpose from the group consisting of: lifting strap for rescuing a human or an animal, lifting strap used in forestry, lifting strap used in agriculture, lifting strap used for transport of goods, lifting strap for leading and unloading ship freight, seizings, safety belt in a vehicle sling having at least one strap and a sliding buckle for the strap, the sliding buckle having a largely U-shaped base part in which a wing is mounted, the wing having a front wing section and a rear wing section, the front wing section together with the U-shaped base part encircling an aperture intended for the strap extending through the aperture, where the wing is mounted pivotably about an axis so that pivoting of the rear wing about the axis in a direction away from the base part forces the front wing section to pivot towards the base part to reduce the aperture for securely locking the strap in the aperture.
 9. A rescue strap (14) sling including a strap for encircling a person , where the strap (14) has two ends (12, 12′) extending through the aperture (9) in a sliding buckle (1) according to claim 1-7, and fastening devices (15) for fastening the strap (14) to a rescue rope and a sliding buckle, with a largely U-shaped base part in which a wing is mounted, the wing having a front wing section and a rear wing section, the front wing section together with the U-shaped base part encircling an aperture, wherein the strap extends through the aperture, wherein the wing is mounted pivotable about an axis so that pivoting of the rear wing about the axis in a direction away from the base part due to pull from the strap bearing against the rear wing section of the wing and having a direction with a component perpendicularly away from the base part, forces the front wing section to pivot towards the base part to reduce the aperture for securely locking the strap in the aperture.
 10. A rescue strap sling according to claim 9, wherein the strap has two ends (12, 12′) are provided with a material enhancing friction at least at one side extending through the aperture of the sliding buckle, and wherein the strap has fastening devices at the two ends for fastening the strap to a rescue rope.
 11. A rescue sling according to claim 10, wherein the two ends are provided with a material enhancing friction at least at one side.
 12. A rescue system comprising a rescue fork and a rescue sling and holders for holding the straps of a rescue sling fastened to the rescue fork, the rescue fork having two fork arms forming a U-shaped front part and a handle extending away from the U-shaped front part, each holder having a first member for fastening the holder to the fork arm and a second member for fastening the holder to the strap, the first member having holding means releasable from the fork arm or the second member having means releasable from the strap. 